As capacitors having a small size, a large capacitance, and low ESR (Equivalent Series Resistance) capacitors, promising candidates are electrolytic capacitors including an anode body on which a dielectric layer is formed, a solid electrolyte layer formed so as to cover at least a part of the dielectric layer, and an electrolytic solution.
For the solid electrolyte layer, a π-conjugated conductive polymer with a dopant is used. It is known that the dopant gradually comes out into the electrolytic solution, which is called as a dedoping phenomenon. Thus, the conductive polymer degrades with time, thereby gradually increasing the ESR of the electrolytic capacitor.
Therefore, it is attempted that a dedoping phenomenon is suppressed by including an acid component in an electrolytic solution to decrease the pH value of the electrolytic solution (See Unexamined Japanese Patent Publication No. 2006-108650).